Businessman Robert Vadra, son-in-law of Congress president Sonia Gandhi, and the DLF group, one of India's leading realty firms, are involved in multi-crore corrupt land deals, said activist Arvind Kejriwal and lawyer Prashant Bhushan at a sensational press conference in Delhi on Friday.

"DLF is giving Robert Vadra cash and selling off properties to him at an extremely cheap rate," alleged Bhushan.

"This will be called the Robert Vadra scam," he alleged.

"Who will even register an FIR against son-in-law of ruling dynasty of country?"

Kejriwal alleged that DLF sold land and properties at cheap rates to Vadra in several parts of the country and in return was given favours by the state Congress goverments.

"Robert Vadra acquired properties worth hundreds of crores (of rupees) from nothing. What is the source of these funds," asked Kejriwal. He distributed scanned copies of documentary evidence to back his claim.

"In the last four years, Robert Vadra has gone on a property buying binge and has purchased at least 31 properties mostly in and around New Delhi, which even at the time of their purchase were worth several hundred crores (of rupees)," Bhushan alleged.

Kejriwal said that between 2007 and 2010 Vadra's wealth grew from Rs. 50 lakh to Rs. 300 crore in three years.

Congress Party president Sonia Gandhi, her daughter Priyanka Gandhi, her son Rahul Gandhi, and husband of Priyanka, Robert Vadra (2L) attend a memorial ceremony for slain former prime minister Rajiv Gandhi on his 19th death anniversary, in New Delhi. AFP photo

Bhushan said the balance sheets of five companies set up by Vadra and his mother show that the "total share capital of these companies was just Rs. 50 lakh".

"All these transactions are in Congress-ruled states. Who will investigate the allegations?" said Kejriwal.

"No government department has the courage to investigate such a powerful, influential person impartially," said Kejriwal.

"This massive property buying spree by the son-in-law of the ruling dynasty in the country gives rise to several important questions," he said.

The Congress termed the allegations "wild and completely unfair".

"The story had come out in the Economic Times earlier. This is an old strategy of Kejriwal... Vadra had explained the position at the time... He pays his income tax and has a right to live as he wants. It is unfair to drag the Congress into it," said Congress MP Sandeep Dikshit.

India Against Corruption (IAC) member Arvind Kejriwal shows documents during the media conference as they accused Congress president Sonia Gandhi's son-in-law Robert Vadra of large-scale corruption in real estate dealings, in New Delhi. HT photo

"Why should anyone have to answer to anyone about any property they have unless there is anything illegal about it," said Dikshit, terming the allegations "wild and completely unfair".

Kejriwal, who was the key strategist of a movement for a strong Lokpal bill, last week made his political debut with a party, whose name is to be announced next month. Prashant Bhushan, his father Shanti and Manish Sisodia are the other key members of his party.